1. D. Kikelj and U. Urleb, in: Science of Synthesis, Georg Thieme Verlag (2002), Vol. 11, p. 627. Chem. Abstr., 139, 6779 (2003).
2. G. Pattenden, J. Heterocycl. Chem., 29, 607 (1992).
3. H. Ulrich, in: Science of Synthesis, Georg Thieme Verlag (2002), Vol. 11, p. 835. Chem. Abstr., 139, 52895 (2003).
4. G. Seybold and H. Eilingsfeld, Liebigs Ann. Chem., 1271 (1979).
5. J. Barker, J. G. Kettle, and A. W. Faull, PCT Int. Appl. WO 9940914; Chem. Abstr., 131, 170342 (1999).